Wash, core and quarter the apples. If you do not have an apple corer, quarter the apple and slice the cores out by cutting off the inside point of each apple quarter. Use a large measuring cup to determine how many cups of apple quarters you have. For every four cups (1 quart) add 1/2 cup of water and a teaspoon of lemon juice to a large pot along with the apples. Bring the apples to a simmer over medium heat, stirring the apples every few minutes until the apples have cooked down so that all the apples are under the liquid line. Continue to simmer the apples until very soft, about 30 minutes. When the apples are very soft and falling apart, remove from the heat and force through a strainer, food mill or potato ricer. Discard the solids. Store apple sauce covered tightly in the refrigerator for a week or two. Apple sauce can also be frozen in small containers for many months.